Evolution of Sexual Dimorphism


Female (left) and male (right) flowering willow catkins. Male catkins abundant in pollen (bottom right).
Female (top) and male (bottom) guppies.
Female (left) and male (right) adult jumping spiders.


About me


Iulia Darolti

Department of  Zoology

University of British Columbia

Vancouver BC, V6T 1Z4, Canada


I am a Postdoctoral Research Fellow in Judith Mank's lab at The University of British Columbia. Through my research, I am interested in understanding the selective forces and mechanisms underlying the evolution of sexually dimorphic traits. My work revolves around the study of sex chromosomes and of differentially expressed genes between males and females. 



PhD in Evolutionary Biology, University College London, UK. Advisor: Prof Judith Mank


BSc (Hons) Zoology (1st Class), The University of Manchester, UK. Dissertation advisor: Dr John Fitzpatrick

Research and travel grants


BBSRC Travel Grant, UCL

Key conference and seminar contributions



Co-organiser, together with researchers at the Universities of East Anglia and of British Columbia, of the Online Evolution and Ecology Seminar Series


Co-organiser of symposium on Mate Preferences and Mating Systems, 2nd Joint Congress on Evolutionary Biology, Montpellier France



Departmental Seminar, Uppsala University, Sweden


Oral Presentation, Evolution Meeting, Providence USA

Oral Presentation, The Evolution of Cooperation and Conflict Symposium, Uppsala Sweden

Science outreach


Speaker at the London Soapbox Science event

- Soapbox Q&A blog



Under construction

The evolution of sexual dimorphism

Despite sharing the majority of their genome, males and females of the same species often show a wealth of phenotypic differences, affecting morphology, physiology, behavior and life history, among other traits. I am broadly interested in how sex-specific evolutionary pressures shape distinct male and female phenotypes. In some species, the two sexes differ by their sex chromosomes, and sex-limited (Y or W) genes partly explain the observed sexual dimorphism. To a large extent, however, sex differences are encoded by genes that are shared between males and females but that are expressed differently in the two sexes (sex-biased genes). In my research, I integrate genomic and transcriptomic data to explore the evolution of sex chromosomes and of sex-biased gene expression and their role in sexual dimorphism.



Sex-biased gene expression

Many sexually dimorphic characteristics have been studied in relation to differential regulation of genes present in both sexes, referred to as sex-biased gene expression. Depending on the sex in which they are predominantly expressed, sex-biased genes can be divided into male-biased or female-biased, with genes showing similar expression between the sexes referred to as unbiased. Sex-biased genes are thought to evolve in response to conflicting sex-specific selection over optimal expression.

I use transcriptomic and bioinformatic tools to study the breadth of differential gene expression within populations and throughout development, and the mechanisms underpinning the evolution of sex-biased genes.



9. Darolti I, Wright AE, Mank JE (2020) Guppy Y chromosome integrity maintained by incomplete recombination suppression. Genome Biology and Evolution in press.

8. Furman BLS, Metzger DCH, Darolti I, Wright AE, Sandkam BA, Almeida P, Shu JJ, Mank JE (2020) Sex chromosome evolution: So many exceptions to the rules. Genome Biology and Evolution in press.


7. Darolti I, Wright AE, Sandkam BA, Morris J, Bloch NI, Farré M, Fuller RC, Bourne GR, Larkin DM, Breden F, Mank JE (2019) Extreme heterogeneity in sex chromosome differentiation and dosage compensation in livebearersProceedings of the National Academy of Sciences 116:19031.

6. Farré M, Li Q, Darolti I, Zhou Y, Damas J, Proskuryakova AA, Kulemzina AI, Chemnick LG, Kim J, Ryder OA, Ma J, Graphodatsky AS, Zhang G, Larkin DM, Lewin HA (2019) An integrated chromosome-scale genome assembly of the Masai giraffe (Giraffa camelopardalis tippelskirchi)GigaScience 8:giz090.

5. Wright AE, Darolti I, Bloch NI, Oostra V, Sandkam BA, Buechel SD, Kolm N, Breden F, Vicoso B, Mank JE (2019) On the power to detect rare recombination eventsProceedings of the National Academy of Sciences 116:12607.



4. Morris J, Darolti I, Bloch NI, Wright AE, Mank JE (2018) Shared and species-specific patterns of nascent Y chromosome evolution in two guppy speciesGenes 9:238.

3. Fox G, Darolti I, Hibbitt JD, Preziosi RF, Fitzpatrick JL, Rowntree JK (2018) Bespoke markers for ex-situ conservation: application, analysis and challenges in the assessment of a population of endangered undulate raysJournal of Zoo and Aquarium Research 6:50-56.

- BBC Earth

- UoM Research Blog

2. Darolti I, Wright AE, Pucholt P, Berlin S, Mank JE (2018) Slow evolution of sex-biased genes in the reproductive tissue of the dioecious plant S. viminalisMolecular Ecology 27:694–708.



1. Wright AE, Darolti I, Bloch NI, Oostra V, Sandkam BA, Buechel SD, Kolm N, Breden F, Vicoso B, Mank JE (2017) Convergent recombination suppression suggests a role of sexual conflict in guppy sex chromosome formationNature Communications 8:14251.


I am very grateful for my PhD research funding from the Biotechnology and Biological Sciences Research Council through the London Interdisciplinary Doctoral Programme.